​The Seahorse Audio Blog

So, how do you meet ACX requirements that you submit recordings that fall within -23 to -18 dB? Is it, in fact, some kind of witchcraft or can anyone do it?

I'm here to tell you, I had no idea how to meet this requirement when I first started recording with Audacity. I thought if the green bar (see illustration above) was within the -23 to -18 range when I was recording, that was (probably) going to be just fine for ACX requirements. Probably ... maybe ... I hoped.

Newsflash: I was WRONG. TERRIBLY WRONG. And, I had to learn the hard way just exactly what ACX was looking for me to do, as a narrator-producer to hit this benchmark.

How do you do it? Let's take it step by step.

Step 1: Record it right. First of all, you need to be recording at the right level. See that little microphone icon above the green bar? You want to be hitting between -12 and -3 on that baby when you are recording live. Below that, and you will definitely need to crank up (amplify) your original recording, which can lead to distortion that *might* not sound good.

Step 2: Finish recording a 3- to 5-minute sample of the chapter you want to submit. We will use this sample to do the next steps.

Step 3: Use the Contrast feature to see what Audacity says about your recording. I like to think of Audacity like my own personal Mr. Spock, giving me the scientific information I need to make those command decisions. Make sure that you have the entire recording highlighted for analysis BEFORE you click the next thing. Then, use Analyze>Contrast. It will look like this when it opens:

Now, you will see you have the choice of measuring the foreground and/or background. You will be using the top MEASURE SELECTION button ONLY. You only need to know what the Foreground measurement is. You don't care about the Background. Contrast with silence is what we care about for ACX requirements.

Next, hit MEASURE SELECTION. You will see a result pop up in the Volume and Contrast Result windows. It will look like this:

Do you see that number in the Volume box? It says -22.39 dB. That's within the target range. That's what you need to see: between -23 and -18 to pass ACX's requirements for RMS. See that other thing? The "Background not yet measured" message? We don't care about that. It's not important for our purposes.

What if your number is too low or too high? We will talk about that in another post. Don't worry. You can (probably) fix it. We definitely have some tools we can try.